1. Field of the Invention
This invention relates to an analog triangular wave output encoder and more particularly to such an encoder in which the analog triangular wave can be obtained by simply changing the light receiving pattern of the fixed slit plate without changing the processing circuit.
2. Prior Art
As the encoder of the above type, there has been proposed and adopted an optical rotary encoder having a structure as shown in FIG. 5. The light receiving masks in the fixed slit plate in such optical rotary encoder are formed with an equal one-pitch interval as shown in FIG. 10.
Hence, the output signals obtained from the slits 1 of the light receiving mask patterns of the aforementioned slit plate are in the form of a sinusoidal wave approximate to a trapezoidal wave, although this has not been specifically indicated in prior art literature.
In the above described conventional encoder, the output waveform presents a linearity only for a range of about 60 percent of the output voltage Vpp. When it is desired to elevate the range of linearity to higher than 60% it has been necessary to modify not only the processing circuit for the output signals, but also the structure of the encoder itself. This results in significantly elevated manufacturing costs of the analog triangular wave output encoder.